The Special Chamber on B1 is reachable via the Kitchen or the Hall of War.
You’ll first need the Iron Insignia Key to unlock the door. When you enter the room, head to the right to find a bricked window sill. Grab the pipe bomb and use it to break the wall to the left of the coffin to reveal a lit torch. Swing the brazier next to the torch to the flame to ignite it. You’ll then need to use the lit brazier to light the unlit brazier on the other side of the room. This will then in turn lower the gate around the coffin allowing you to collect the Azure Eye. We found it easiest to push the brazier using small nudges as it helped to control the movement better. It will also help to start swinging the other brazier to get them closer together. Please note that the physics on the braziers is greatly off so it might take a while to line them up perfectly in order to light the last brazier.